Preheat oven to 350 degrees F (175 degrees C). Grease one 2 quart casserole dish and set aside.
Blend together the sweet potatoes, evaporated milk, orange juice, vanilla, sugar, salt, 3 tablespoons butter, nutmeg and cinnamon. Pour into prepared casserole dish.
Prepare the topping by mixing together the 1/3 cup butter, brown sugar, flour and pecans. Sprinkle over casserole and bake for 45 minutes or until hot.